At present, white LEDs are to be produced. If a white phosphor is not coated with a single color LED, the red, green and blue LEDs are mixed together; National Taiwan University (NTU) Researchers are developing a technology that produces single-pixel (pix) white light from a single layered-column LED.
The above technology is an ongoing research by a team led by Yang Zhizhong, a professor at the Institute of Photonics and Optoelectronics of Taiwan University. The basic concept is to embed quantum wells on the same substrate and grow closely. Gallium nitride (GaN) and indium gallium nitride (InGaN) nano-rods. Yang Zhizhong pointed out that those LED arrays are fabricated by organic metal chemical vapor deposition (MOCVD) pulse growth method, which can achieve better luminescence performance than traditional process technology.
“We can grow multi-section nano-pillars of different cross-section sizes, which can display a wider emission spectrum than a single-section nano-column;†Yang Zhizhong said in an exclusive interview with the editor of EE Times US edition: "Our goal in developing this multi-section nanopillar LED is to emit white light that is free of phosphors."
Scanning electron microscopy images show that a single-diameter columnar pixel emits a single color of light (left), but if the top is narrowed (right), the same pixel emits two different shades of light; With a narrow layer, it is possible to emit a third color light, that is, a single pixel emits white light mixed with three colors of red, green, and blue (RGB).
Yang Zhizhong said that this sidewall emission may be more efficient because there will be a larger surface area; by vertically expanding pyramids of different diameters, even more light can be emitted in each nanocolumn. In combination with a properly balanced red, green and blue (RGB) light source, this method should also produce a variety of white light in cool and warm tones.
Using reverse-doped gallium nitride and a quantum well sandwiched in between, researchers at Taiwan University show how GaN LEDs work
“We can also use gallium zinc oxide (GaZnO) instead of indium tin oxide (IoT) as a transparent interconnect, which has very high conductivity;†Yang Zhizhong said that his research team is also developing surface plasma. Enhance luminescence, increase efficiency and avoid the droop effect; and increase visible bandwidth high-speed communication by increasing the bandwidth. â€
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